In order to facilitate maintenance of a conventional printer that employs electrophotography as well as communications equipment and copiers that use such a printer, often use is made of a removable cartridge within which a consumable such as toner is sealed.
FIG. 2 is a block diagram illustrating an example of the hardware configuration of a typical color-image forming apparatus 30 that uses color cartridges of different colors.
As shown in FIG. 2, the apparatus includes a host interface 1 through which the image forming apparatus 30 communicates with a host computer, which is not shown. A communication signal from the image forming apparatus 30 to the host computer is output to the latter via the host interface 1. A communication signal from the host computer to the image forming apparatus 30 enters the latter through the host interface 1.
A host communication line 2 is used as the communication medium between the image forming apparatus 30 and the host computer. Data, e.g., image processing information, which enters the image forming apparatus 30 as code data via the host interface 1 first is stored in a receive buffer RAM 4, which receives data from the host computer, under the control of a CPU 3. The receive buffer RAM 4 stores character code, graphic forming information and control information, etc., in the order in which these are sent from the host interface 1.
A font memory 9 stores character pattern data in association with character codes.
A processing program such as an interpreter that analyzes the code data such as character code, graphic forming information and control information and forms a dot pattern has been stored in a program ROM 6. In accordance with the processing program, the CPU 3 reads corresponding character pattern data out of the font memory 9 based upon the character code data that has been stored in the receive buffer RAM 4, and expands this data into a pattern in a dot-pattern memory 10.
A control program for exercising overall control of the image forming apparatus 30 is stored in the program ROM 6, and the CPU 3 controls the overall image forming apparatus 30 in accordance with this program.
A work random-access memory (working RAM) 5 is a memory for writing and reading various data temporarily. This memory is utilized while the CPU 3 is executing processing in accordance with the program stored in the program ROM 6.
The dot-pattern memory 10 is a memory for storing data-pattern data that has been expanded into a pattern by the processing program stored in the program ROM 6 in order to form the dot pattern.
The dot-pattern data from the dot-pattern memory 10 is input to the FIFO (First In, First Out) memory 7, which outputs this data to an interface 8 for an image forming unit 20.
The interface 8 sends the image data (dot-pattern data) from the FIFO memory 7 to the image forming unit 20. The latter forms the image data, which has been received via the interface 8, on a recording medium such as paper by a well-known electrophotographic method, thereby producing an output of the image.
A control panel 13 such as a keyboard or touch-sensitive panel is used by the operator to make inputs for configuring the operating environment of the image forming apparatus 30. For example, the control panel 13 is to set the on-line/off-line status of the host interface 1.
A sensor 14 for a toner-cartridge exchange button senses that the operator has pressed a toner-cartridge exchange button disposed on the image forming apparatus 30 proper or on the control panel 13.
Signals that enter from the control panel 13 and button sensor 14 are input to a data bus 15 and address bus 16 via a control-panel interface 12. It should be noted that the configuring of the operating environment of the image forming apparatus 30 can be performed not only by the control panel 13 but also from the host computer via the host interface 1.
An environment configuring memory 11 comprising a non-volatile read/write memory (referred to as an “NVRAM” below) saves various operating environment settings of the image forming apparatus 30.
A sensor 18 for a toner-cartridge exchange cover senses whether a cover for exchanging toner cartridges used by the image forming unit 20 is open or closed.
A toner-cartridge sensor 19 senses which toner cartridge [either a Y (yellow), M (magenta), C (cyan) or K (black) cartridge] is presently situated at a removal port as well as the amount of toner remaining in the cartridge.
A clock signal that is output from a clock generating circuit 17 is used as the clock signal of the CPU 3.
It is assumed that the color-image forming apparatus shown in FIG. 2 requires toners of the four colors Y (yellow), M (magenta), C (cyan) and K (black) for the purpose of forming color images. In general, a toner cartridge is provided for each of the colors so that the toner cartridges for the individual colors can be replaced and replenished one at a time.
When such a color toner cartridge is exchanged, as shown in FIG. 4, a cylindrical supporting body 40 that supports the toner cartridges of the individual colors must be moved from a position (A) for when an image is formed to a position (B) for exchanging the toner cartridge (this is performed in a toner-cartridge exchange mode). Further, since only a single toner cartridge generally can be exchanged at one time at the toner-cartridge removal port, it is necessary to rotate the supporting body 40 in such a manner that the color toner cartridge to be exchanged will arrive at the removal port.
In the conventional image forming apparatus, the main body of the apparatus is provided with the toner-cartridge exchange button, as mentioned above. The supporting body 40 rotates through a predetermined angle in a predetermined direction in response to depression of the toner-cartridge exchange button. Whenever the supporting body 40 is thus rotated, the color toner cartridges move to the toner-cartridge removal port one after another.
The user who is exchanging a toner cartridge presses the toner-cartridge exchange button until the desired color toner cartridge moves to the removal port. The user then exchanges the cartridge.
The toner-cartridge exchange button and its related control function, which are not used frequently, result in higher cost for parts.
Further, if the toner-cartridge exchange button is mounted at an exposed location on the apparatus surface, such as on the control panel, there is a possibility that the button will be pressed by the user accidentally during image formation processing or at the time of an anomaly. This makes it difficult to create the control program and to deal with exception handling.
Further, the positional relationship between the color toner cartridge desired to be exchanged and the toner-cartridge removal port differs from one time to another. In certain cases, therefore, replacing a toner cartridge becomes a laborious task. For example, if the supporting body 40 rotates through ¼ of a revolution counter-clockwise in FIG. 4 whenever the toner-cartridge exchange button is pressed, then, in order to exchange the black toner cartridge (K), the toner-cartridge exchange button must be pressed three times to move the toners in the order cyan (C), magenta (M) and black (K) so that the black toner cartridge will arrive at the removal port.
According to a method proposed heretofore, the opening and closing of the toner-cartridge exchange cover is used instead of depression of the toner-cartridge exchange button. Though this method is advantageous to a certain extent in that it prevents erroneous operation, labor is still involved in moving the cartridge desired to be exchanged. Hence, there is still room for improvement.